Lifting-magnet.



I N0. 837,174. PATENTED NOV. 27, 1906.

' G. E. F. AHLM.

LIPTING MAGNET; APPLICATION FILED MAY22,1906.

a citizen. of the United States, residing at loading a dt f irig pig-iron and scrap UNITED: STATES PATEN OFFICE- CHARLES E. F. AHLM, OF CLEVELAND, OHIO, ASSIGNOR TO CLEVELAND ARMATURE WORKS, OF CLEVELAND, OHIO, A PARTNERSHIP.

LIFTlNG-MAGNETQ Specification of Letters Patent.

To all whom i't may concern Be a known thatI, CHARLES E. F. AHLM,

Cleveland in the county of Cuyahoga and State of hio, have invented a certain new and useful Improvement in'Lifting-Magnets,

' {of which the following is a-full, clean, and exjact description.

This inve t1on relates to certain improvements designed to be used in loading and unandarticles'capable of-magnetization, and more" articularly relates to a construction sep arate' where y small articles packed in pilessuch as nails,-a'xles, and castingsmay be handled in bulk. Heretofore when fiat bottomed.

magnets have been employed for this purpose the results have not been satisfacto owing ,to the fact that the magnetic flux woiil d travel in the path of least reluctance between the oles and thus skim merely the surface oft e pile. It has been attempted to overcome this defect by causing the flux to approach the central pole normal to the surface thereof, and it has been sought to accomplish this effect by constructing the magnet so that the frame extends both outside of the coil and partly through the same. This last-mentioned structure I have not found satisfactory and do not use, as it does not seem to me to be based on the essential prinf These COIlS have separate outer poles which extend over and embrace their respective coils, and they are each Wound so that the .ma netio flux passes to a common inner pole which extends entirely through the upper coil and does not cxtend within the lower coil or coils. This construction is not so subject to loss in leakage as the ty e previousl referred to ,in which a single cm is used, wit

one of the oles extending outside of the coil and the ot er partly through the same. v My construction is attended by further advanta es, whichwill appear from the description be ow, whereby it will be shown how the magnetic flux is forced to enter deep into the mass of the material instead of being'allowed to pass merely over the surface.

material.

any waste in the way of leakage.

In the accompanying drawings, Figure Tie a vertlcal cross-section of a magnet in which I have used three separate coils placed con-- centrically about a common central pole-Q piece, each succeeding coil being below the plane of the inner coils. Fig.2 is a plan view of the same. f

Referring to the'figures, it will beseen that the frame A of the magnet, which is preferably 'a casting of great magnetic permeability, is, as shown" in Fig. 1, provlded with three annular concentric magnetic coils B B B, held'in channels A on its lower face by a retaining-frame C, suitably sha ed, which bracket is of brass or some equivalent It will be seen that the frame is cup-shaped and that the inner or centraLpolepiece A extends entirely through the inner coil, so that its polar face A is on the same lane with onslightly below the plane of the ower face of the inmost 'coil B, thus avoiding The upper planeof the next outer coil is below the plane of the said olar face A and is emraced on each si e by depending annular p0le-pieces A A The outermost coil, B is ikewise below the pole-piece A and the lower plane of the intermediate coil B and is embraced on each side b the depending annular ole-pieces A an A". It is obvious that t iis structure can be expanded to any amount within practical limits and any numfatente d Nov. 27, 1906.

her of coils be used according to the requirements of the magnet. Any suitable means may be emplo ed for retaining the coils in their grooves; ut the frame 0 which I have shown is annular and has upwardly-extending braces at intervals to support the innermost and intermediate coils and a flat ring for sup orting the outermost coil and is a simple orm easily and'cheaply constructed; but it is obvious that other means may be em loyed.

he several coils are so wound that the magnetic flux passes around each in the same direction, thus enabling me with a properllyconstructed ma netto have the centra p0 epiece of one o arity and each of the outer pole-pieces o a polarity opposite to that of the central poleiece. W been thou ht t at this condition of affairs could not e maintained, such opinion has been'based upon the idea that if currentsc it has hitherto I 5 square inches.

second coil B that a 3 5 dotted arrows in Fig. 1.

5o penetrate deeper and. (ice same direction their combined effects onthe intervening pole-piece would be neutralized.

Such, however, is notthe case if the magnet magnets l have constructed. If a circular section of this magnet be taken at the radial distance a, the cut surface will present approximately two hundred and fifty-four A circular section around the magnet at the radial distance 2') and 0 will each present about two hundred and eighty-five square inches in cross-section. A similar cut on the line d will give two hundred and seven square inches in cross-secti on. A similar cut on the line e will give one hundred and ten square inches in cross-section. Thus it will be seen that the magnetic capacity passing from the central pole-piece through the body of the magnet to the outermost polepiece is diminished to such an extent that while the entire flow can pass through the body of the magnet o'ver the innermost coil B the resistance will become so great in passing over the ortion of the flux will pass out through the intermediate polepiece ,A' between the first and second coils, and the same division of the Bow will take place in passing over the third coil B as indicated by With the proportions indicated this action inevitably takes place. I

When such a magnet is lowered onto the material to be lifted and the. inner coil ener 4.0 gised, the upper layer of the material is mag- 4 5 ward, and if more than two cons used action and result are th The magnetism create rates each successivelayc netic flux of each sue coil satussthe outer coil to al into the pile, thns magnetizing a greater. quantity of the in ateriel and causin the ll X from the outer poles by reason of being forced inward toward the center of the pile of material to ap- The total area of the face of the inner pole is two hun- IO died and fifty-four square inches in one of the proach the central or inner polo along lines normal to the surface of the latter. This results'in endowing the magnet with the high- 651; lifting capacity.

Ipreferably connect up the coils in parallel in order to obtain a certain manipulative advantage in handling small articles. When such. articles are transferred to the point of discharge, either the cntire lot may be (lroppecl .'at once by opening the circuitsof the coils at the same time or the material may be dropped gradually by opening the circuits of each coil successively, beginning with the outer coil. This latter procedure may be used to advantage where it is desired to distribute the material handled.

Having thus described my invention, I claim 1. A lifting-magnet having a central polepiece and two or more pole-pieces encircling said central pole-piece, being of a polarity opposite to thatcf the central pole-piece and having their polar faces below the plane of the face of the central polo-piece.

2. A lifting-magnet having a central polepiece, and two or more polepieces enveloping said central pole-piece, and depending below the polar face of the central pole-piece.

3. A lifting-magnet having a central polepiece and two or more depending pole-pieces extending below the polar face of the central pole-piece and enveloping the latter, each of said depending pole-pieces havin a polarity opposite to that of the central pole-piece 4. A lifting-magnet having a central polepiece and two or more surrounding polepieces depending below the plane of the polar lace of the central pole-piece, and coils for said depending pole-pieces, said coils being in parallel.

5. A lifting-rnagnet comprising a top plate having three or more pole-pieces depending therefrom, one of which pole-pieces is enveloped within the others, coils arranged on said depending pole pieces, each of the nner pole pieces passing entirely through the coii ranged thereon and. terminating above the plane of the next outer coil.

in testimony whereof I hereunto aflhr my signature inthe resence of twowitncsses.

HARLES E. i AHLM.

Witnesses:

' J. M. WOOD'WARD,

H. R. SULLIVAN. 

